Vector Tile Cartography Considerations

I. Layer Data Content

II. Layer Properties Settings

III. Thematic Maps

IV. Text Style

V. Point Symbols

VI. Line Symbols

VII. Symbols

VIII. Map Properties Settings

IX. Vector Tile Generation Configuration

X. Vector Tile Update

This article summarizes the SuperMap map styles and settings that SuperMap vector tiles can and cannot support, clearly defining the capability boundaries to assist users in creating vector maps suitable for vector tile production.

SuperMap supports generating vector tiles (.mvt) that comply with the MapBox MVT specification. Tile data includes the geometric shapes and attributes of features, while the styling of features is described by MapBox standard style files (style.json), following the MapBox GL version 8 style specification. For details on MapBox styles, please refer to: https://www.mapbox.com/mapbox-gl-style-spec.

SuperMap-generated vector tiles are displayed on SuperMap iClient clients based on MapBox style files. Clients use MapBox GL or OpenLayers to render vector tiles; OpenLayers supports rendering vector tiles in various projections, while MapBox GL only supports rendering vector tiles in the EPSG3857 projection.

When generating vector tiles, the program needs to convert SuperMap map styles to MapBox style descriptions. However, some SuperMap map styles and settings are not supported by MapBox and cannot be converted, resulting in inconsistencies between the display effects of SuperMap maps and vector tiles after generation, or loss of certain style and map setting effects.

Map Content, Rendering Styles, and Related Configurations		Supported in Vector Tiles	Remarks
I. Layer Data Content
Vector Dataset	2D point, line, polygon, and text datasets	Supported	Raster data layers are not supported. If a map contains unsupported dataset layers, generating vector tiles will ignore these layers. If a geometry contains too many sub-objects, it may affect tile generation speed during vector tile creation. It is recommended to split sub-objects to improve efficiency.
	3D point, line, polygon, and text datasets	Supported
	Tsinghua Shaanxi Surveying and Mapping (EPS) point, line, polygon, and text datasets	Supported
	Other datasets	Not supported
Geometry Complexity			For massive polygon data, simplification is required to improve vector tile generation and display efficiency. Users can enable simplification based on actual data conditions. For data sources other than PostGIS, simplification during vector tile generation is specified by the "rarefy display" parameter. Checking this option enables simplification; otherwise, it is disabled. For PostGIS data sources, modify the SuperMap.xml file (located in the SuperMap iDesktopX installation directory/Bin/) by adding the "<MVTSimplifyPGIS>TRUE</MVTSimplifyPGIS>" tag. The default parameter value is TRUE, meaning simplification is enabled; FALSE disables it. For densely noded and complex-shaped polygon objects at small scales, simplification may cause deformation in the resulting vector tiles. For example: At small scales, polygonal rivers may deform significantly after simplification. It is recommended that maps have reasonable complexity at different display scales; specifically, use line objects to represent rivers at small scales. For massive earth polygon data, simplification at small scales may cause hollowing issues due to deformation. It is advisable to create vector pyramids for such data before generating vector tiles.
Vector Data Coordinate System			If the data coordinate system differs from the map display coordinate system, the system will convert the coordinate system during vector tile generation. For large datasets, this conversion consumes significant disk space and time. It is recommended to convert the data coordinate system to the map display coordinate system before generating vector tiles.
II. Layer Properties Settings
Layer Visible Scales	Maximum and minimum visible scales	Supported	Vector tiles are created using global scales. The visible scale range of layers in the vector map must be adjusted to match global scales; otherwise, the visibility of map features in vector tiles may not match the original map. The numerical values and precision of layer visible scales must exactly match the global scales.
Layer Display Filter	Filter expression	Partially supported	Only simple logical relationship judgments and comparison operations are supported. Comparison operations support =, <, >, !=. Values in expressions must be numerical; text or characters are not supported, e.g., "NAME = 'Sichuan Province'" is unsupported. Logical judgments: Support And, Or, Not Field names in filter expressions must not include table names, e.g., "China_Province.pop_2014 > 3833" is unsupported.
Layer Join Attribute Table Settings		Not supported
Aggregation of Normal Layers and Thematic Layers			In the same map, for the same point/line/region dataset, at most one thematic map and one label thematic map based on that dataset can coexist; otherwise, unexpected effects may occur. In the same map, for the same point dataset, at most one unique value thematic map and one single-value label thematic map based on that dataset can coexist, and they must use the same single-value field. Alternative approach: If multiple thematic maps are needed for one point/line/region dataset, use layer groups for separation. Create multiple layer groups, ensuring each group contains at most one thematic map and one label thematic map per point/line/region dataset. Within the same layer group, for a point dataset, at most one unique value thematic map and one single-value label thematic map can coexist, using the same single-value field. Labels and their corresponding vector layers must be in the same layer group, with the label layer above the vector layer.
Layer Blend Mode		Not supported
Scale with Map		Not supported
Weight		Not supported
Simplification Display Settings		Not supported
Filter Small Overlapping Objects Settings		Not supported
Object Display Order		Not supported
III. Thematic Maps
Unique Value Thematic Map	Single value expression	Partially supported	Only single fields are supported; field expressions and SQL function calculations are not supported, e.g., name \|\| ‘_’\|\| type. Note: Objects with NULL field values are not displayed in vector tiles.
	Property field defining marker style	Partially supported	Versions 12.0.0 and above support only point unique value thematic maps using fields to control symbol rotation angle styles. Other property field settings for symbols, colors, sizes, or rotation angles are not supported.
	Thematic layer offset settings	Not supported
	Marker style	Partially supported	Support details refer to the "Point Symbols," "Line Symbols," and "Symbols" sections.
	Traffic situation configuration	Not supported
Graduated Color Thematic Map	Segmentation expression	Supported	Currently, only single fields are supported; field expressions and SQL function calculations are not supported.
	Segmentation method	Supported
	Segmentation precision	Supported
	Marker style	Partially supported	Support details refer to the "Point Symbols," "Line Symbols," and "Symbols" sections.
Uniform Label Thematic Map	Label expression	Partially supported	For label fields used in label thematic maps, only single fields are supported; field expressions and SQL function calculations are not supported, e.g., name \|\| ‘_’\|\| type.
	Label background	Partially supported	Background shape: Supported for rectangle, rounded rectangle, and point symbols; not supported for diamond, ellipse, triangle. Background style: Only pure filling is supported; rounded rectangle backgrounds support fill borders, but rectangles do not. Background margin: Supported Background shadow effect: Not supported When both a point normal layer and a label thematic map based on it exist for the same point dataset, MapBox does not support setting both point symbols and label backgrounds; otherwise, point symbols are lost, and label backgrounds may misalign from text. When point symbols are used for label backgrounds, they do not resize automatically with label length.
	Label offset	Supported
	Leader line	Not supported
	Label alignment with point	Partially supported	Left baseline, right baseline, and central baseline alignments are not supported.
	Overlap and avoidance settings (flow, no overlap)	Not supported	MapBox handles feature avoidance differently from SuperMap, leading to differences in label count, alignment, etc.
	Text layout (long text handling, line breaks, multi-line alignment, landscape display tags)	Not supported	MapBox handles long label line breaks differently. If label thematic maps use line break or multi-line text settings, vector tile display effects may differ significantly.
	Text avoidance of tile range	Not supported
	Label height range	Not supported
	Text style settings	Partially supported	Support details refer to the "Text Style" section.
	Label along-line display direction	Partially supported	MapBox styles support only two along-line directions (normal to line and top-to-bottom, left-to-right). If other directions are set in the map, vector tiles use "top-to-bottom, left-to-right."
	Show slivers	Not supported
	Along-line label character spacing	Supported (Supported in versions 12.0.0 and above)	MapBox handles labels along lines differently from SuperMap, so vector tile displays may vary, e.g., periodic spacing effects. When fixed text angle is set for labels along lines, "along-line label drawing type" must be set to entire draw; otherwise, fixed text angle is invalid in vector tiles.
	Along-line character relative angle	Not supported
	Label along-line mode	Not supported
	Fixed text angle	Supported
	Remove duplicate labels	Not supported
	Along-line periodic spacing	Supported
	Along-line label drawing type (split draw, entire draw, compatible draw, etc.)	Not supported
Single Value Label Thematic Map	Single value field	Partially supported	Only single fields are supported; field expressions and SQL function calculations are not supported, e.g., name \|\| ‘_’\|\| type. For the same point dataset, if both a unique value thematic map and a single-value label thematic map exist, they must use the same single-value field.
Single Value Label Thematic Map	Other settings content	Consistent with uniform label thematic map
Custom thematic map		Not supported	If a map contains unsupported thematic maps, generating vector tiles will ignore these layers.
Composite label thematic map		Not supported
Matrix label thematic map		Not supported
Graduated symbol thematic map		Not supported
Statistical thematic map		Not supported
Dot density thematic map		Not supported
Aggregation maps (heat maps, grid maps, etc.)		Not supported
IV. Text Style
Font		Supported	Ensure corresponding font files exist on the computer.
Text color		Supported
Font size		Supported
Font Effect	Bold	Supported	When bold or italic effects are used, ensure corresponding bold and italic font files exist on the computer for valid effects in vector tiles.
	Italic	Supported
	Outline	Supported
	Shadow	Not supported
	Underline	Not supported
	Strikethrough	Not supported
	Rotation angle	Supported
	Slant (left slant, right slant, slant angle)	Not supported
	Fixed size	Supported	During vector tile generation, set text to fixed size in the map; otherwise, tile display may differ from the original map.
	Text background	Not supported	Text backgrounds appear as outlines in vector tiles.
	Superscript/subscript	Not supported
Text layout	Multi-line text alignment, etc.	Not supported
V. Point Symbols
System point symbols	System0	Not supported	System0 square symbols appear as circles in vector tiles. Workaround: Create a custom point symbol with a square geometry.
System point symbols	System1	Supported
Vector point symbols		Supported
Raster point symbols		Supported
Color		Supported
Symbol rotation angle		Supported
Symbol transparency		Not supported
Scale with map		Not supported
VI. Line Symbols
System line types	System0, System1	Supported
System line types	System2, System3, System4	Not supported	System2, System3, and System4 line types appear as solid lines in vector tiles. Workaround: Create a custom line type, add dash sub-lines (system line type), and adjust virtual-real modes to achieve dashed lines.
Custom line types		Supported	Custom line types support multiple sub-lines, but each sub-line type must be "default."
Sub-line types	Dash (system line type)	Supported	Virtual-real mode is supported.
Sub-line types	Other sub-line types	Not supported	Unsupported sub-lines appear as solid lines in vector tiles.
Sub-line settings	End symbol	Not supported
Sub-line settings	Sub-line offset	Not supported
Scale with map		Not supported
VII. Symbols
System symbols	System0, System1, System2, System3, System4, System5, System6, System7	Supported
Symbol borders		Consistent with line symbols	MapBox style support for polygon symbol outlines aligns with line symbol support.
Custom symbols		Supported	Custom symbols support only one filling sub-layer, which can be image filling or symbol fill.
Symbol sub-layers	Symbol filling	Supported	Versions below 12.0.0 support symbols with one sub-layer; filling methods include point symbol filling, picture fill, pure filling, and linear filling. Versions 12.0.0 and above support symbols with multiple sub-layers; filling methods include point symbol filling, picture fill, pure filling, and linear filling.
Symbol sub-layers	Image filling	Supported
Scale with map		Not supported
VIII. Map Properties Settings
Map fixed scales		Supported	Vector tiles are created using global scales. The fixed scales of the vector map must be adjusted to match global scales; otherwise, feature visibility in vector tiles may not match the original map. The numerical values and precision of layer visible scales must exactly match the global scales.
Map overlap settings		Not supported	Versions 12.0.0 and above only support disabling the "show/hide points with text" map overlap setting.
Fixed symbol angle		Not supported
Fixed text angle		Not supported
Fixed text direction		Not supported
Line antialiasing		Not supported
Text antialiasing		Not supported
Label weight settings		Not supported
IX. Vector Tile Generation Configuration
Tile scales	Global scales	Supported
Tile scales	Custom scales	Not supported
Tile level range	Continuous scale levels	Supported
Tile level range	Non-continuous scale levels	Supported	If scale levels are discontinuous, display effects may be abnormal for missing levels in vector tiles.
Storage format	Compact	Supported
	Original	Supported
	MongoDB	Supported
Storage path	Local directory	Supported